Concentration of minerals

ABSTRACT

Mineral aggregates, especially ores, that are found dispersed over a widespread remote area such as the ocean floor are gathered and at least partially separated from silt to concentrate minerals for transport to the sea surface. Mineral concentrator is adapted for movement over the deep sea floor and has means for gathering and separating dispersed mineral aggregates to provide a concentration of desired minerals for transport to the sea surface.

Sullivan CONCENTRATION OF MINERALS [75] Inventor: Arthur F. Sullivan, Redmond,

Wash.

[73] Assignee: The International Nickel Company,

Inc New York, N.Y.

[22] Filed: Dec. 2l, 1972 [2!] Appl. No.: 317,166

[52] US. Cl. 299/8, 37/57 [51] Int. Cl E02f 7/00 [58] Field of Search 299/8 [56] References Cited I UNITED STATES PATENTS 3,588,174

6/1971 Rossfelder.... 299/8' 11 3,802,740 11 Apr. 9, 1974' 3,740,098 6/1973 Lachnit 299/8 Primary Examiner-Ernest R Purser 5 7 ABSTRACT Mineral aggregates, especially ores, that are found dispersedover a widespread remote area such as the ocean floor are gathered and at least partially separated from silt to concentrate minerals for transport to s 15 Claims, 7 Drawing Figures PATENTED 9 974 SHEET 1 [If 3 ?ATENIEUAPR 9 1914 saw 2 or 3 SHEET 3 OF 3 PATENTED APR. 9

CONCENTRATION OF MINERALS The present invention relates to obtaining minerals from thedeep sea and particularly relates to concentrating, e.g gathering and separating, solid minerals located on the ocean floor or at the bottoms of other bodies of water. a Q a It is well known that manganese nodules are found in varying quantities in or on the abyssal silt of the worlds oceans. Collectively these nodules are a thinly distributed mineral ore resource of large areal extent. Utilization of undersea ores, including manganese nodules and other metallic or nonmetallic solid aggregates, requires special apparatus and methods for gathering solid bodies from floorsof deep seas, such as depths of 5,000 to 15,000 or more feet.

In general, manganese nodules may be visualized as somewhat spheroidal or ellipsoidal concretions of solid material lying buried to about half their diameters in fine clay silt. Although the precise physical nature and behavior of the undisturbed nodule-silt matrix is not well understood at this time, some ocean floor areas where nodules are found are typified by a soft, adhesive, cohesive bed of fine clay silt mostly composed of silt particles of sizes of about 1 or 2 microns.

Heretofore, conveying means such as fluid transport by pumping and/or suction or by. mechanical hoisting have been devisedfor conveying minerals from the deep sea floor to a ship. or platform floating at the sea surface. However, in addition to means for conveying undersea minerals to the surface, there are needs for efficiently gatheringor collecting undersea minerals into a concentration at the in-take or entrance of undersea transport apparatus for carrying the minerals to the surface. In view of the great depths at which many undersea minerals are found, it is desirable to have a mining vehicle that can sweep an undersea mineral bed efficiently without need for a human to go to the sea bottom. Also, when considering the great water pressures encountered at the deep sea bottom, it is desirable to have a vehicle that can concentrate undersea minerals without requiring many or highly complex electrical or other power operated components and yet perform efficiently on irregular and varying undersea floors. m

Now, the present invention has discovered an apparatus and a method whereby undersea mineral aggregates that are located over arelatively wide spread area of the sea floor can be concentrated into a relatively small'space for transport to the sea surface.

It is an object of the present invention to provide apparatus for concentration of mineral aggregates.

The invention also provides a process for concentrating mineral aggregates. 7

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawing in which: i

FIG. 1 is a plan view of an embodiment of the mineral concentrator of the invention;

FIG. 2 illustratesa side view, with a vertical section taken on line 2 2 of FIG. I, of the mineral concentrator of FIG. 1 on the sea floor.

FIG. 3 shows a detail view, on a larger scale, in longitudinal cross-section, of a portion of the entrance to'the embodiment of FIGS. 1 and 2.

FIG. 4 is a plan view of another embodiment of the concentrator of the invention;

FIG. 5 is a side view of a vertical section taken on line 5 5 of FIG. 4;

FIG. 6 is a side view of a vertical section taken on line 6 6of FIG. 4; and s FIG. 7 is a perspective view depicting an embodiment of the mineral concentrator of the invention on the sea floor in combination with apparatus for conveying minerals up to a vessel on the sea surface. I

In accordance with the present invention, manganese nodules or other ore aggregates located at a silt floor of an ocean or other water body having a floor comprising a soft silt are pressed downward into the silt, and the ore and silt are compacted together to produce an ore-silt matrix with a substantially flat upper surface. A portion'of the ore-silt. matrix is sheared, or similarly horizontally separated, from the lower portion of the sea floor and is moved upwardly a short distance above the sea floor into a partially enclosed compartment where at least some of the silt is separated from the ore and rejected from the concentrator, advantageously by washing silt from the ore with moving water, while a major portion of the ore is retained in the compartment. Thereafter, the retained ore is moved through a conduit and funneled to an in-take location where an upward conveyance apparatus can transport the minerals to the sea surface. In this connectiomthe invention provides an undersea mineral concentrating vehicle which is especially satisfactory for sweeping a path through an ore-bearing undersea floor and gathering and concentrating ore for conveyance to the sea surface. Accordingly, the invention provides a mineral concentrator vehicle comprising a vehicle body having a substantially flat underside surface extending the width of the path that is desired to be swept, a forlike, duct having between the entrance and exit thereof.

a wash zone with duct fenestrations (openings) of sizes satisfactory for enabling exhaust of water and silt and for retaining nodules in the duct, and a rearwardly and upwardly sloping guide extending from the plow blade to the wider portion of the ductfAdvantageously, the

- concentrator also has a water impeller and a conduit adapted for leading a flow of water to the impeller and then directing a flow of water from the impeller to the wash zone in the duct.

The sloping front surface (which may be a smooth curve inasmuch as a curve is a continuously varying slope) and the flat bottom surface of the concentrator vehicle function together to depress and restrain aggregates and irregularities at the silt surface and thereby form a compacted surface zone or matrix of aggregates and silt with a smooth, flat, upper surface. Thus, nodules and other ore aggregates that are naturally dispersed at varying heights are, by action of the vehicle, positioned and concentrated in a shallow surface zone, e.g., depths down to about -2 or 4 inches below the compacted surface. Moreover, in areas where the silt has thixotropic characteristics, the pressure of the vehicle i can fluidize the silt and thus aid in separation of mineralaggregates from silt. The weight and bottom surface area of the vehicle are desirably proportioned to provide an average downward pressure of about A to 1 psi (pounds per'square inch) on the sea floor. Fluidization of the silt may also be enhanced by open orifices, pressurized water jets, directed downwardly through the vehicle body. Advantageously, the center of gravity of the vehicle is aft of the center of horizontal area of the body, e.g., about above or aft of the leading edge of the plow. i

The plow blade on the concentrator vehicle serves to shear a desired portion of the ore-silt matrix from the sea floor and, accordingly, the distance of the blade below the bottom of the vehicle body is set to be sufficiently large for permitting passage of desired sizes of mineral aggregates while rejecting excessively large aggregates. For instance, for gathering manganese nodules the plow blade is advantageously about 2% inches below the underside of the vehicle body. Location of the plow blade below and'aft (at or near the rear of the body and any event behind the center of gravity 'of the vehicle) 'is particularly important for achieving good directional stability and is beneficial for regularly consistent and efficient sweeping of large areas of irregularly-surfaced sea floors to collect desired sizes of mineral aggregates.

Additionally, the aft-located plow and the special lower and front (or bow) surfaces on the vehicle inhibit disadvantageous creation of a traveling bow wave of silt in front of. the vehicle.

Where desired, the outboard portions of the plow can be angled forwardly in order to aid sweeping material inward toward the centerline of the vehicle.

The concentrator vehicle of the invention can be towed by a sea going vessel with a cable or conduit connected from the towing vessel (or an undersea extension thereof) to a forward portion of the vehicle and then the minerals concentrated by the vehicle can be transported to the towing vessel by an upward flow of water through a conduit from the concentrator duct to the towing vehicle. Or, independent towing and ore carrying vehicles can be used, or the concentrator can have its own motive power, e.g., electrically powered tracks. Even further, it would not be beyond the invention if it is desired to deposit the concentrated nodules on the sea floor and later pick them up with another vehicle.

Advantageously, for enabling prolonged operation at the seabottom, the concentrator vehicle has means for cleaning solid matter from the passageabove the plow and means for closing the passage to prevent entrance of additional solids.

If desired, a crusher may be incorporated with the vehicle to reduce the sizes of the gathered aggregates.

Referring now to the'accompanying drawing, FIGS. 1 and 2 show concentrator vehicle comprising body 11, upwardly sloping leading face'12, plow 13, screen 14, duct and hollow ball joint 16. Blade 17 of the plow is held below the body by gussets 18 which are attached to vehicle bottom (underside) face 19 and to the plow blade and serve to hold the plow blade at a controlled distance below the bottom face of the body. Thus, the blade and the bottom face form the lower and upper surfaces of entrance 20 and the gussets form entrance sides. The passage, 21, behind the entrance has a rearwardlyincreasing vertical cross-section, which is obtained with the gradual upward sweep 22 at a short portion of the body behind the leading edge of the plow. The gussets restrict the entrance opening, functioning like a grizzly, and thus the horizontal spacing of the gussets serves as an aid for controlling the maximum size of aggregate that is gathered into the concentrator. Horizontal spacing of the gussets is desirably about 3 inches, or 2 or 4 inches, apart. Furthermore, the downwardly rearward slant, e.g., 20 or 30, of the gusset leading edges, 23, results in oversize aggregates or accumulations of silt, mud, debris, etc., being pushed downward and also helps the concentrator body to ride over rigid obstacles and prevents snagging on solid plate-like formations, e.g., manganese concretions or undersea pavement. Trailing or guide portion 24 of the plow has a rearward and upward curvature for directing upwardly a flow of fluid and solid 'matter from the entrance. Accordingly, inasmuch as the screen extends upward from the trailing portion of the plow, material dislodged from the ocean floor by the plow blade is directed upwardly in front of the screen and toward the duct. j

The illustrated concentrator also comprises header 25 having injector nozzles 26 directed toward the screen. Advantageously, the injector nozzles are disposed forward of the screen and are orientedand adapted to direct water flow from the header rearwardly and upwardly toward the screen, which is preferably a wedge-wire screen or deck or a wedge-bar gratingNozzle 26A which is specially directed downwardly above the plow blade aids in fluidizing the silt.

The sides of the header, duct and plow are'closed sufficiently to prevent desired aggregates from escaping by sideward flow. The outside gussets, 18A, one at each side of vehicle 10, extend back to the header. The interior gussets, which are between the sides, can have a relatively short cross-section in the rearward direction, e.g., bars, as in a grizzly. Water for washing material between the header and the screen is brought in at suction inlet 27, transmitted through conduit 28, impelled at increased velocity by water fan 29 and guided to the header by impeller discharge conduit 30. Water flow direction is indicated by. arrows on the drawing. It should be noted that the suction inlet is disposed over the forward portion of the concentrator body and substantially above, e.g., 2 or 4 or more feet above, the vehicle body and thus is in position to takein clean water for washing. Accordingly, the wash water conduit, which includes the impeller discharge duct, provides for intake of water and for directing a flow of water to the header and thence to the screen.- The concentrator can be towed along the floor of the sea by a riser pipe attached to the hollow ball joint or by a tow cable attached near the bow of the vehicle.

The leading face of the concentrator, which curves (or slopes) forwardly and upwardly, is particularly important as a means for depressing and compacting material in the path being swept by the vehicle.

When in operation on the floor of the sea, the leading face depresses nodules 31 and other irregularities of sea floor 32 and somewhat compacts silt 33 to form a compacted concentrated subsurface zone as depicted at 34. While the forward motion of the collector body continues, the plow blade passes below nodules and compacted silt at the entrance under the collector body and then the trailing portion of the plow directs silt and nodules in an upward flow between the header nozzles and the screen. Water flow from the nozzles washes much of the silt rearward out through screen 14 at the stern while nodules are retained and funneled forward in duct 15, where some remaining silt can be exhausted through forward screen 35.

The vertical depth of the entrance opening to the collector is maintained by the gussets in combination with the plow blade and the underside of the vehicle body. Between periods of use, the entrance opening size can be adjusted by replacing the gussets with different sized gussets or supplementing the gussets with spacers. Or, a remotely controlled power driven support can be usedto hold the plow and vary the plow depth,thereby providing remotely variable control of the maximum size .of nodule, or other solid aggregate, that will be accepted by the concentrator. The size of aggregate that will be rejected from the concentrator is controlled by the openings in the screen.

While the plan view of FIG. 1 depicts a concentrator wherein the entire plow extends'perpendicular to the centerline, modifications of the depicted concentrator can be built with the outboard portions of the plow disposed at angles forward of the perpendicular, such as with the outer half or two-thirds of each arm of the plow angled up to about 30 or 45 forward of a perpendicular to the centerline of the vehicle.

An advantageous means for clearing the entrance and shutting off flow of material into the concentrator is illustrated in FIG. 3, which shows shut-off gate 36 attached to shaft 37 with both gate and shaft nested in the lower portion of body 11, between a pair of gussets. Theshut'off gate is movable from the open position (as illustrated to the closed position (depicted with broken Jet 26A is specially directed over the'plow in orderto beneficiate fluidization of material in the entrance.

Referring now to FIGS. 4, 5 and 6, concentrator vehicle 41 hasbody 42 with upward sloping leading face 43 and forwardly angled plow 44 attached to the body with gussets 45 which have leading edges 46 extending forwardly and sloping forwardly and upwardly from the plow blade. The plow comprises blade 47 and rearwardly upward sloping guide 48. Duct 49 extends upward from the plow guide and leads to hollow ball joint 50 which joins the duct to riser pipe 51 for conveying material to a collecting station. Inlet orifices 52 and 53 enable local water to be drawn into the duct, e.g., when water is being moved from the duct to the riser pipe. The duct has a fenestrated portion made of wedge-wire screen, comprising wedge-wires 54 and bands 55, that extends upward from the forwardly swept outboard portions of the plow and provides openings for outflow of silt while retaining desired aggregates. The forward angle A of the plow arms directs aggregates toward the center of the vehicle, where the aggregates can be drawn up in the duct. Sizes and locations of the inlet orward out through the wedge-wire screen in the fenes.-

trated portion.

Body plate orifices 56 disposed forwardly of the plow enable a flow of water to be induced downward through the orifice openings and under the body when movement of the body over softsilt results in a low pressure area at the body-silt interface, and are thereby advantageous for fluidizing the silt. Also, flow of water through orifice 52 is beneficial for fluidization at the central portion of the plow.

FIG. 7 is aperspective view, partially enlarged, illustrating concentrator 10 towed with cable 60 from powered floating vessel 61. Riser pipe 62 which is rotatably connected to the ball joint on duct 15 of the collector provides a closed passage for flow of desired minerals up from the duct to the surface vessel while silt is exhausted through aft screen 14 and forward screen 35. Upward flow of nodules is assisted by pump means 63 and by the pressure differential between the ocean floor depth at the concentrator and the exit of the riser at the surface vessel. Electricalpower is transmitted down to the concentrator by cable 64 from the surface ship. I v

The present invention is particularly applicable to undersea mining of manganese nodules that are naturally scattered on the ocean floor. Of course, the utility of the invention is not limited to obtaining manganese nodules and in view of the foregoing description it will beevident that the invention is applicable to undersea mining, concentrating, gathering, collecting, etc., other desired materials that are present at or near the surface 6 lfices and the openings in the fenestrated portion are designed to enable drawing water and aggregates through the duct while some water and silt flow rearof marine floors. For instance, it is contemplated that the invention can be used for obtaining phosphate concretions from the sea floor.

Furthermore, it should be observed that the invention gives consideration to the important matter of conservation of the natural environment. The invention enables concentrating valuable mineral aggregates and discharging a substantial proportion, e.g., a major proportion of one-half or more, or essentially all, of the disturbed silt out of the concentrator while the concentrator is 'on the ocean floor, thereby restricting the amount of silt or other undesired fine material that otherwise might be transportedto the upper levels of the ocean. Also, it is noteworthy that the invention enables avoiding disturbing the ocean floor in'areas outside the path that the vehicle sweeps to obtain desired materials.

Although the present invention has been described in conjunction with-preferred embodiments, it is to be un- I derstood thatmodifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Suchmoditications and variations are considered to be within the purview and scope of the invention and appended claims. I

I claim:

1. Apparatus for concentrating desired mineral aggregates lying dispersed in a preselected path over a mineral bed on an undersea floor in order to facilitate transport of the desired mineral aggregates to the sea surface comprising:

a. a vehicle body having a flat bottom surface extending transverselythe horizontal width of the preselected path;

b. compacting means for forcing mineral aggregates and sea floor silt in front of the vehicle body down- 7 wardly into the sea floor when said body is moved forwardly on the sea floor in the preselected path and for thereby forming a concentration of mineral aggregates in a subsurface silt zone in the preselected path;

c. shearing means for shearing loose from the sea floor at least a portion of the aforesaid mineral aggregat'e concentration when the aft portion of the vehicle body moves over the concentration;

d. guide means for imparting an upward movement to at least a portion of the mineral aggregate concentration that'is sheared loose by the shear means and also for-guiding desired aggregates in'the upwardly moving portion to a preselected location where the desired aggregates can be transported to the sea surface; and

e. separation and discharge means for separating un- I desired silt from desired aggregates in said upwardly moved portion and for discharging silt from the apparatus while the apparatus is on the ocean floor; i

2. Apparatus as set forth in claim 1 which also comprises water guide and power-driven impeller means for directing a flow'of substantially silt-free water through the separation and discharge means to forcibly wash silt from the upwardly moved portion and assist in discharging silt from the apparatus while on the sea floor.

3.-Apparatus adapted for being assembled to provide a vehicle forundersea mining of solid mineral aggregates comprising:

a. a body having a flat bottom surface and adapted to be moved in a forward direction on the undersea b. a leading-face member at the front of the body and having a forwardly and upwardly sloping forward surface;

c. a plow having a blade and a sloping guide surface and disposed under the rear portion of the body with the blade at a preselected distance below the bottom surface of the body and with the guide surface extending rearward and-upward from the plow blade;

d. a partially open duct extending upward from the guide surface of the-plow; and

e. a fenestrated surfacecommunicating with said duct and adapted for separating desired aggregates from undesired fine material and for discharging a substantial proportion of the undesired fines and retaining desired aggregates while the vehicle is on the undersea floor.

4. A vehicle for sweeping a preselected path in an undersea bed of desired mineral aggregates dispersed over an area of the undersea floor and for concentrating desired mineral aggregates lying in said path in order to facilitate transport of the minerals to the sea surface comprising:

a. a vehicle body having a flat bottomsurface and adapted to be moved forwardly on the undersea floor;

b. a forwardly and upwardly sloping leading-face surface extending from the front of the body;

c. a plow attached to the body, said plow having a blade extending forwardly and transversely in relation to the body and having a rearwardly and upwardly sloping guide surface and being disposed with the plow blade below the bottom surface of 8 the body at a distance sufficient to provide an entry and a passage between the blade and the body of sizes sufficient for enabling entry and passage of desired aggregates and for preventing entry of undesirably large aggregates; and

d. a partially enclosed mineral carrier duct mounted on the body, said duct having a duct entrance extending from an upper portion of the guide surface of the plow and having a duct exit remote from the duct entrance and also having openings in the duct between the entrance and the exit, said openings being of sizes sufficiently small to enable retaining desired aggregates in the duct and sufficiently large to enable discharging particles of sizes smaller than the desired aggregates out of the duct while the vehicle is on the ocean floor.

5. A vehicle as set forth in claim 4 having:

a. a wash water conduit with a water entrance above the vehicle body and leading into the mineral carrier duct of thevehicle; and

. an impeller for forcing a flow of water through the wash water conduit;

c. said wash water conduit and impeller being adaptedin combination with the mineral carrier duct to direct a flow of water into and out of the duct at a location between the 'duct entrance and exit and to wash undesired particles away from desired aggregates and thence out ofthe duct and thereby enhance the discharging of small particles out of the duct while the vehicle is on the ocean floor.

I 6. A vehicle as set forth in claim 4.having orifice means for directing a flow of water downward under the body to enhance fluidization of the silt.

7. A vehicle as set forth in claim 4 having means for forcing material outward from the entry to the passage.

8. A vehicle as set forth in claim 4 having a means for shutting-off flow of material into the passage.

9 A vehicle as set forth in claim 4 having the weight of the vehicle and the bottom surface area of the body proportioned to provide an average downwardpressure of about 41 to 1 pound per square inch on the undersea floor.

10. A vehicle'as set forth in claim 4 having gusset plates at the entrance between the plow blade and the body and spaced apart sufficiently for enabling entry of desired aggregates and for assisting prevention of entry of undesirably large aggregates.

1 l. A vehicle as set forth in claim 10 wherein the gusset plates have forwardly and upwardly sloping leading edges.

12. A vehicle as set forth in claim 4 having the outboard portions of the plow disposed at angles forward of a perpendicular to the longitudinal axis of the body.

13. A vehicle as set forth in claim 4 having the body and the plow extending transversely the horizontal width of the preselected path.

14. A vehicle as set forth in claim 4 wherein the leading edge of the plow is disposed behind the center of gravity of the vehicle.

15. A process for providing a concentration of mineral aggregates, initially dispersed on an undersea floor, for transportation to the sea surface comprising:

a. forcing mineral aggregates and'sea floor silt down into the sea floor to thereby form a smooth upper tion upwardly above the sea floor;

d. then washing silt from the mineral aggregates in the upwardly moved concentration while retaining the mineral aggregates; and

e. moving the washed retained aggregates to a means for transporting the aggregates to a vessel at the sea surface. 

1. Apparatus for concentrating desired mineral aggregates lying dispersed in a preselected path over a mineral bed on an undersea floor in order to facilitate transport of the desired mineral aggregates to the sea surface comprising: a. a vehicle body having a flat bottom surface extending transversely the horizontal width of the preselected path; b. compacting means for forcing mineral aggregates and sea floor silt in front of the vehicle body downwardly into the sea floor when said body is moved forwardly on the sea floor in the preselected path and for thereby forming a concentration of mineral aggregates in a subsurface silt zone in the preselected path; c. shearing means for shearing loose from the sea floor at least a portion of the aforesaid mineral aggregate concentration when the aft portion of the vehicle body moves over the concentration; d. guide means for imparting an upward movement to at least a portion of the mineral aggregate concentration that is sheared loose by the shear means and also for guiding desired aggregates in the upwardly moving portion to a preselected location where the desired aggregates can be transported to the sea surface; and e. separation and discharge means for separating undesired silt from desired aggregates in said upwardly moved portion and for discharging silt from the apparatus while the apparatus is on the ocean floor.
 2. Apparatus as set forth in claim 1 which also comprises water guide and power-driven impeller means for directing a flow of substantially silt-free water through the separation and discharge means to forcibly wash silt from the upwardly moved portion and assist in discharging silt from the apparatus while on the sea floor.
 3. Apparatus adapted for being assembled to provide a vehicle for undersea mining of solid mineral aggregates comprising: a. a body having a flat bottom surface and adapted to be moved in a forward direction on the undersea floor; b. a leading-face member at the front of the body and having a forwardly and upwardly sloping forward surface; c. a plow having a blade and a sloping guide surface and disposed under the rear portion of the body with the blade at a preselected distance below the bottom surface of the body and with the guide surface extending rearward and upward from the plow blade; d. a partially open duct extending upward from the guide surface of the plow; and e. a fenestrated surface communicating with said duct and adapted for separating desired aggregates from undesired fine material and for discharging a substantial proportion of the undesired fines and retaining desired aggregates while the vehicle is on the undersea floor.
 4. A vehicle for sweeping a preselected path in an undersea bed of desired mineral aggregates dispersed over an area of the undersea floor and for concentrating desired mineral aggregates lying in said path in order to facilitate transport of the minerals to the sea surface comprising: a. a vehicle body having a flat bottom surface and adapted to be moved forwardly on the undersea floor; b. a forwardly and upwardly sloping leading-face surface extending from the front of the body; c. a plow attached to the body, said plow having a blade extending forwardly and transversely in relation to the body and having a rearwardly and upwardly sloping guide surface and being disposed with the plow blade below the bottom surface of the body at a distance sufficient to provide an entry and a passage between the blade and the body of sizes sufficient for enabling entry and passage of desired aggregates and for preventing entry of undesirably large aggregates; and d. a partially enclosed mineral carrier duct mounted on the body, said duct having a duct entrance extending from an upper portion of the guide surface of the plow and having a duct exit remote from the duct entrance and also having openings in the duct between the entrance and the exit, said openings being of sizes sufficiently small to enable retaining desired aggregates in the duct and sufficiently large to enable discharging particles of sizes smaller than the desired aggregates out of the duct while the vehicle is on the ocean floor.
 5. A vehicle as set forth in claim 4 having: a. a wash water conduit with a water entrance above the vehicle body and leading into the mineral carrier duct of the vehicle; and b. an impeller for forcing a flow of water through the wash water conduit; c. said wash water conduit and impeller being adapted in combination with the mineral carrier duct to direct a flow of water into and out of the duct at a location between the duct entrance and exit and to wash undesired particles away from desired aggregates and thence out of the duct and thereby enhance the discharging of small particles out of the duct while the vehicle is on the ocean floor.
 6. A vehicle as set forth in claim 4 having orifice means for directing a flow of water downward under the body to enhance fluidization of the silt.
 7. A vehicle as set forth in claim 4 having means for forcing material outward from the entry to the passage.
 8. A vehicle as set forth in claim 4 having a means for shutting-off flow of material into the passage.
 9. A vehicle as set forth in claim 4 having the weight of the vehicle and the bottom surface area of the body proportioned to provide an average downward pressure of about 1/4 to 1 pound per square inch on the undersea floor.
 10. A vehicle as set forth in claim 4 having gusset plates at the entrance between the plow blade and the body and spaced apart sufficiently for enabling entry of desired aggregates and for assisting prevention of entry of undesirably large aggregates.
 11. A vehicle as set forth in claim 10 wherein the gusset plates have forwardly and upwardly sloping leading edges.
 12. A vehicle as set forth in claim 4 having the outboard portions of the plow disposed at angles forward of a perpendicular to the longitudinal axis of the body.
 13. A vehicle as set forth in claim 4 having the body and the plow extending transversely the horizontal width of the preselected path.
 14. A vehicle as set forth in claim 4 wherein the leading edge of the plow is disposed behind the center of gravity of the vehicle.
 15. A process for providing a concentration of mineral aggregates, initially dispersed on an undersea floor, for transportation to the sea surface comprising: a. forcing mineral aggregates and sea floor silt down into the sea floor to thereby form a smooth upper surface on a portion of the sea floor and concomitantly form a concentration of mineral aggregates in a subsurface silt zone extending below the smoothed upper surface; b. shearing loose from the sea floor at least a portion of the thereby formed mineral aggregate concentration in said subsurface zone; c. moving the sheared mineral aggregate concentration upwardly above the sea floor; d. then washing silt from the mineral aggregates in the upwardly moved concentration while retaining the mineral aggregates; and e. moving the washed retained aggregates to a means for transporting the aggregates to a vessel at the sea surface. 